linux-kernel - Re: [PATCH RFC 00/11] lock monitor: Separate features related to lock

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Date:	Thu, 18 Mar 2010 14:59:29 +0900
From:	Hitoshi Mitake <mitake@....info.waseda.ac.jp>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Frederic Weisbecker <fweisbec@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel@...r.kernel.org, h.mitake@...il.com,
	Paul Mackerras <paulus@...ba.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Jens Axboe <jens.axboe@...cle.com>,
	Jason Baron <jbaron@...hat.com>
Subject: Re: [PATCH RFC 00/11] lock monitor: Separate features related to
 lock

On 03/17/10 18:52, Ingo Molnar wrote:
 >
 > * Frederic Weisbecker<fweisbec@...il.com>  wrote:
 >
 >>> You add chained indirect calls into all lock ops, that's got to hurt.
 >>
 >> Well, the idea was not bad at the first glance. It was separating 
lockdep
 >> and lock events codes.
 >>
 >> But indeed, the indirect calls plus the locking are not good for 
such a fast
 >> path.
 >
 > What would be nice to have is some sort of dynamic patching approach 
to enable
 > _both_ lockdep, lockstat and perf lock.
 >
 > If TRACE_EVENT() tracepoints were patchable we could use them. (but 
they arent
 > right now)

I'll try it!

And I have a question related to this dynamic patching approach for lockdep.
If dynamic proving turning on/off is provided,
lockdep will be confused by inconsistency of lock acquiring log.

Will the sequence,

lock_acquire(l) -> turning off -> lock_release(l) -> turning on -> 
lock_acquire(l)

detected as double acquiring?

Should turning on/off lockdep be done in the time
when every processes have no lock?

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